Cross-grooved pulley



Patented den. 53-9, 1923.

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MILTON F. WILLIAMS, GI LGUIS, IVIISSOUEI, ASSIGNOR 0F FORTY NINE ONE-HUNIDRED'IIIS 'lO HAROLD 1V5. PLAISTED, OF ST. LOUIS, MISSOURI.

CROSS-GROOVED PULLEY.

Application filed March 21, 1821. Serial No. 454,157.

To all whom it may concern Be it known that I, Minion lViLLri-iirs, acitizen of the United States, residii at St. Louis, State of Missouri,have in? ented certain new and useful Improvements in Cross-GroovedPulleys, of which the following is a specification.

This invention relates to certain new and useful improvements inpulleys, the peculiarities of which will be fully described and claimed.I

The main object of my invention is to provide a pulley, the normal faceof which is provided with cross grooves of such shape as to improve,when rotating, the belt contact between a beltand pulley face, wherebymore power is transmitted from belt to pulley, or vice versa; secondly,to reduce the whistling or humming sound of a grooved face pulley; andthirdly, to increase the tendency of the belt to hug the grooved face ofa pulley. I

In my prior application on pulleys Patent No. 1,423,476 dated July 18,1922, I have shown and described a pulley face having cross grooves,eachgroove being formed by a radial face, and an opposing face slantingaclzward with regard to the direction of rotation, and 'pplied to thenormal face of a crown face pulley and a straight face pulley.

That form of pulley tested out a greater efficiency than a plain facepulley, but when its direction of rotation was reversed so that theslant side inclined forward '31 regard to the direction of rotation, theefiiciency obtained was even greater.

It was due to this discovery and after careful tests had been made tosubstantiate the same, that a pulley having a face grooved in accordancewith the present application was designed and tested out, and will nowbe described.

In the accompanying drawing on which like reference letters indicatecorresponding parts, Fig. 1 represents a side elevation of a crown facepulley exemplifying my invention and mounted on a shaft shown insection. and having a belt indicated in broken lines as drivipg saidpulley; Fig. 2 a partial face view of said pulley and partial sectiononthe line 2-2 of Fig. 1; and Fig.

3 an enlarged detail View across the shaft in section of a portion ofsuch a pulley face.

In carryin out the improved design suggested by the. tests abovementioned, a plain faced crown pulley was transversely grooved withgrooves having opposing faces 'i and B (Fig. 1) that are inclined towardeach other, and make an obtuse angle with the portion of the normal facerespectively adjacent'as more plainly shown in the enlargci'l view, Fig.These faces A and meet in an intersecting line or surface C thatispractically parallel with the shaft D on which the pulley is mounted,so that when a crown face pulley provided wit-h grooves having faces Aand B inclined as shown and described, thegrooves formed in the normalface are substantially as shown in the face view Fig. 2 herein. That isto sayythe width of each groove circumferen ially, decreases froin thecentral plane K (Fig. 2) toward each end of the pulley. The slantingfaces A and B likewise decrease from the said central plane X towardsthe ends of the pulley; and the radial depth of the groove similarlydecreases from the central plane to the ends of the pulley. It is prevferred that the inclination of the faces A. and B toward one another,(whether intersecting at a line C as described or otherwise,) shouldpresent an angle of degrees or more,'that is, an obtuse angle,-forreasons that will appear hereafter.

Whatever the inclination toward each other of opposing faces of the samegroove may be, the angle a and Z) (Fig; 3) made by the respective facesA and .B with the adjacent normal face of the pulley, should he anobtuse angle. Thus in Fig. 3 this angle between the opposing faces A andB in a groove is practically 120 degrees; and the angles of said faceswith the lSSl'JQCtlVQ. nor mal faceindicated by a and Z aresubstantially 120 degrees as shown.

It has been found by carefu tests un iler simi r circumstances to the,tests made .ipon 1 crown face pulley and a pulley grooved according tothat described in said p ior application, that the power transmitted bythe belt to a pulley having grooves as in the present application and ofsimilar di ameter, (that IS, 8",) was 29 lgzi. This is l i-Hf greater or100' plain face pulley. Again. t c H er or 20% greater than the pullexertc said belt against the radial ace of a Furthermore and finally,this is 2l:;,. or 9% greater than the pull exerted belt upon the slantface of a'i'adial and faced groove, as above stated.

Thus I have discovered that a pulley face having grooves the opposingfaces of which are substantially as shown in the drawing herewith, iscapable of'much greater elliciency, namely lOO%,-than a. plain facepulley; secondly, that it is 20% greater effciency when compared with aradial face groove; and thirdly, that it is 9% greater ween comparedwith a groove only one of which races is slanting, and that forward inthe direct-ion of rotation. it is believed that by a sl ant the greaterefficiency thus obtained by grooves as in the present implication, :5due to the following reasons:

deferring to Fig. 3,-when a pulley is rotating in the direction of thearrow there shown. the surface of the pulley not.

covered by the belt (that is. between the advancing and recedingportions of the belt,) drag along with the face of the pulley a certainamount of adjacent air by frictional. action thereon. As is well lrnownin the science pertaining thereto, the friction of the air upon anadjacent suriace rela: tively stationary, retards the flow of aircurrents at such surface so that the rife?- ti-ve area. (such as that ofan air tube trans mitting air currents,) is reduced in tain definiteamounts. In a similar way with the air currents from the approachingbelt driven against the revolving pulley the friction of the air uponthe surface of a pulley as shown, causes air currents that are slowerand relatively hat-l:- ward adjacent to the pulley face, and causes suchair currents to be deflected into the grooves in the normal face. Whensuch grooves are as shown in this application, the flow of air into andout ofsaid grooves will be facilitated by the slanting sides Pi and 13;under high speed, this travel of the air into and out of the grooveswill tend to form a rarelication in said grooves. lVheii the belttherefore covers such grooves as in ll" l. the rareficalion thusprinhrrcd will va y atmospheric pressure and tend to press the belt withgreater effect upon the normal face of the pulley between the grooves,and likewise into the grooves themsel es, when they are formed as shownin this application. Thus not only will the cushioned air brought in bythe approaching portion of the belt be deflected laterally by saidgrooves in the pulley face, but the readiness of discharge of the airfrom grooves herein shown and described, produces an added atmosphericiaaaaia pressure due to the partial vacuum obtained by the flow of aircurrents into and out of said grooves in a readier manner and withgreater effect than when the grooves are formed according to the priorapplication first above mentioned. Thus in said prior application, thehalf filled grooves formed by the radial face of a pulley r0tating asshown in Fig. 1 of that patent, would tend to support or bridge over theair currents endeavoring to enter said V groove; and when such a pulleyis rotated in the opposite direction (that is, withthe slant faceforward,) the radial face mentioned will obstruct the ready discharge ofthe air entering said grooves. In my present application this bridgingover of the air currents, and obstruct-ion to discharge of said currentsfrom the grooves, is avoided by the advance or forward inclined face Aand'rearward inclined. face B makingthe respective angles a and Z) withthe adjacent normal facewhich angles are substantially.

identical. It is on account of this discovery of the improvedefficiency. of'a groove having both sides or opposing faces formed asherein described, that I claim such a groove face broadly, and do notconfine myself to any particular obtuse angle between said faces-and thenormal face of the pulley. In the tests above described, an 8 crown facepulley was provided with 22 grooves in its circumference, and eachgroove was substantially a quarter of an inch in circumferential widthat the central plane X of said face, and diminishing in width towardsthe ends according to the crown of the pulley, substantially as shown.limit myself to the exact spacenient or center to center distance of thesaid grooves, but state that the grooves in the pulley as tested abovewhere substantially 1- 2; inches center to center.

I claim:

1. A high speed circular pulley provided with transverse grooves,one ofthe opposing faces of each groove making an obtuse angle greater than aright angle with the normal face adjacent to each groove.

2.. .et high speed circular pulley provided with transversegrooves-430th of the opposing faces of each groove making an ob- I donot tuse angle greater than a right angle with the normal face adjacentto each groove.

3. A high speed circular pulley provided with transverse grooves,--theopposing faces of each groove forming an obtuse angle eater than a rightangle with the norma iaceut. and the width of each face IrlC'e 21L-diniiiiishing from the center toward each end of the pulley.

f. A high speed'crown face circular pulley provided with transv rsegrooves,the

opposing faces of each groove forining an obtuse angle with the ad acentnormal face of the pulley, and the circumferential Width of each grooveat the normal face being greatest at the center of the face anddiminishing toward the ends of the pulley.

5. A high speed circular pulley provided in its normal face Withtransverse grooves having opposing faces making an obtuse angle witheach other and also with the portions of the normal face adj acentl toeach groove.

In testimony whereof I have affixed my signature.

MILTON F. WILLIAMS.

